Undersea pipelines may be formed from sections of steel pipe having factory-applied corrosion protection and insulating coatings. During the manufacture of insulated pipe, the ends of the pipe must be left bare to prevent damage to the coating when the pipes are joined in the field by welding. Typically, the insulation layer is cut back from the end of the pipe to form a chamfer which is spaced from the end of the pipe. A lip of the corrosion protection layer may protrude beyond the end (or “toe”) of the chamfer. The chamfering step is typically performed in the factory as part of the manufacturing process.
The individual pipe sections are joined together in the field to form a continuous pipeline. The joints between the pipe sections are known as “field joints”, and are formed by butt welding the pipe sections together, and then applying a layer of insulation over the bare pipe surrounding the weld joint. These steps may be performed as the pipeline is being reeled onto or from a lay vessel (so called “tie-in joints”), during pre-fabrication of multi-jointed pipe strings, or immediately before laying of the pipeline. For reasons of economy, field joints must be rapidly formed and cooled to an acceptable temperature so as not to slow down the reeling or laying operation.
Processes for applying field joints to pipelines are disclosed in commonly assigned U.S. patent application Ser. No. 12/794,402 by Jackson et al., which was published as US 2011/0297316 A1 on Dec. 8, 2011, and which is incorporated herein by reference in its entirety.
There is increasing demand in the oil and gas industry for higher performance coatings to insulate and protect off-shore transport conduits operating at temperatures from about 150° C. to above 200° C. Examples of high temperature resistant pipeline coatings are disclosed in commonly assigned U.S. Provisional Patent Application No. 61/863,976 by Wan et al., filed on Aug. 8, 2013, and in U.S. patent application Ser. No. 14/193,663 by Edmondson et al., filed on Feb. 28, 2014, both of which are incorporated herein by reference in their entireties.
Conventional field joint materials such as epoxy corrosion protection coatings and polyolefin insulation layers may not be suitable for use in field joints for pipelines operating at temperatures from about 150° C. to above 200° C. Therefore, there remains a need for reliable field joint systems for use in high temperature fluid and/or gas transport conduits such as oil and gas pipelines, particularly those operating at these high temperatures.